This invention relates to controllers for garden, farm and other field machinery and specifically to tethering and steering apparatus for such machinery.
Various types equipment have been designed through the years for controlling the operation of self-propelled power equipment used in large open expanses where repetitive passes are needed and no obstacles are present to be steered around.
Haupt, U.S. Pat. No. 3,627,071, describes a tethering device for self-propelled machines. A tether cord is wound in loop formation about control stakes in the center of a field. The free end of the cord is connected to a self-propelled mowing machine for guiding the machine in generally spiral path about a flat base as it unwinds the cord from the spaced winding stakes.
Ramer, U.S. Pat. No. 3,273,664, describes a remote automatic control for a power driven tractor. This control has a movable dolly which is fixedly positionable at various specific locations. A round take-up spool is mounted on the dolly for taking-up or pay-out tether cords to control a spiral path. A dual tether cord arrangement has a main cord connected to one side of a steering rod and a spring-loaded counter part connected to the other side of the steering rod for keeping the wheels of the tractor in a slight outward cant by said spring force.
Jensen, U.S. Pat. No. 3,744,223, describes a tether apparatus for controlling the path of a self-propelled lawn mower in a closing or decreasing spiral path. A round take-up spool is staked to the ground and the self-propelled mower is guided inwardly as the tether cord is wound upon the spool, thereby automatically drawing in the mower to the point of anchorage of the spool. A trip rod shuts off the mower as it reaches the take-up spool.
Goodwin, U.S. Pat. No. 3,853,069, describes a steering apparatus for a wheeled vehicle whereby a follower wheel is caused to travel in a rectangular guideway. This follower wheel is connected through a follower bar to control the operation of the vehicle steering assembly.
The prior art tether-control devices control the "shape" of the tractor path with the "shape" of the take-up spool. Primarily, the paths are spirals, i.e., closing "circles" because the take-up spools are round. Haupt, who uses an elongate "stake" take-up arrangement, also describes an essentially spiral path, i.e. closing/expanding circular paths.
However, as most fields or areas to be plowed or mowed are rectangular, it is desirable to provide a control apparatus which will allow for an elongate or oval or rectangular path rather than a circular one.
What is desired is a control apparatus for controlling the operation of a self-propelled tractor in a rectangular field.
An object of this invention is to provide a tether control for a self-propelled tractor including a take-up or pay-out spool to control the operation of the tractor to travel elongate paths.
A second object of this invention is to provide an elongate guideway upon which said take-up spool operates, the combined operation of said take-up spool and its movement along said guideway acting to control the "shape" of the tractor path.
A further object of this invention is to control the take-up operation of the tether cable to conform to and control a specific tractor "width".
Another object of this invention is to provide a permanent guideway which is buried in a field or a lawn and is out of sight.
Another object of this invention is to provide a trolley upon which said take-up spool rides, said trolley along and being removable from the guideway.
An even further object of this invention is to provide the tractor with a steering control tied to and operated by the tether cable connection.